langbein.org: Molds for Meshes: Computing Smooth Parting Lines and Undercut Removal

Contents

W. Li, R. R. Martin, F. C. Langbein

IEEE Transactions on Automation Science, 6(3):423-432, 2009.

[DOI: 10.1109/TASE.2009.2021324][Preprint]

We consider the problem of computing a parting line for a mold for a complex mesh model, given a parting direction, and the related problem of removing small undercuts, either pre-existing, or resulting from the parting line. Existing parting line algorithms are unsuitable for use with complex meshes: the faceted nature of such models leads to a parting line which zig-zags or wanders across the surface undesirably. Our method computes a smooth parting line which runs through a band of triangles whose normals are approximately perpendicular to the parting direction. We generate a skeleton of this triangle band to find its distinct topological cycles, and to decompose it into simple pieces. After selecting paths making a good cycle, we generate a final smooth parting line by iteratively improving the geometry of this cycle. Compliance in the physical material, and/or modifications to eliminate minor undercuts ensure that such a parting line is practically useful.

@ARTICLE{Li2009,
  author =       {Weishi Li and Ralph R Martin and Frank C Langbein},
  title =        {Molds for Meshes: Computing Smooth Parting Lines and
                  Undercut Removal},
  journal =      {IEEE Trans. Automation Science and Engineering},
  volume =       {6},
  issue =        {3},
  pages =        {423--432},
  year =         {2009},
  abstract =     {We consider the problem of computing a parting line
                  for a mold for a complex mesh model, given a parting
                  direction, and the related problem of removing small
                  undercuts, either pre-existing, or resulting from
                  the parting line. Existing parting line algorithms
                  are unsuitable for use with complex meshes: the
                  faceted nature of such models leads to a parting
                  line which zig-zags or wanders across the surface
                  undesirably. Our method computes a smooth parting
                  line which runs through a band of triangles whose
                  normals are approximately perpendicular to the
                  parting direction. We generate a skeleton of this
                  triangle band to find its distinct topological
                  cycles, and to decompose it into simple pieces.
                  After selecting paths making a good cycle, we
                  generate a final smooth parting line by iteratively
                  improving the geometry of this cycle. Compliance in
                  the physical material, and/or modifications to
                  eliminate minor undercuts ensure that such a parting
                  line is practically useful.},
}

Cite as Molds for Meshes: Computing Smooth Parting Lines and Undercut Removal, http://www.langbein.org/research/manifolds/smoothing/mfm by Frank C Langbein [ 6/August/2009, 11:53].

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